Close inbreeding and low genetic diversity in Inner Asian human populations despite geographical exogamy

turko-mongol-indo-iranian

Open access Close inbreeding and low genetic diversity in Inner Asian human populations despite geographical exogamy, by Marchi et al. Scientific Reports (2018) 8:9397.

Abstract (emphasis mine):

When closely related individuals mate, they produce inbred offspring, which often have lower fitness than outbred ones. Geographical exogamy, by favouring matings between distant individuals, is thought to be an inbreeding avoidance mechanism; however, no data has clearly tested this prediction. Here, we took advantage of the diversity of matrimonial systems in humans to explore the impact of geographical exogamy on genetic diversity and inbreeding. We collected ethno-demographic data for 1,344 individuals in 16 populations from two Inner Asian cultural groups with contrasting dispersal behaviours (Turko-Mongols and Indo-Iranians) and genotyped genome-wide single nucleotide polymorphisms in 503 individuals. We estimated the population exogamy rate and confirmed the expected dispersal differences: Turko-Mongols are geographically more exogamous than Indo-Iranians. Unexpectedly, across populations, exogamy patterns correlated neither with the proportion of inbred individuals nor with their genetic diversity. Even more surprisingly, among Turko-Mongols, descendants from exogamous couples were significantly more inbred than descendants from endogamous couples, except for large distances (>40 km). Overall, 37% of the descendants from exogamous couples were closely inbred. This suggests that in Inner Asia, geographical exogamy is neither efficient in increasing genetic diversity nor in avoiding inbreeding, which might be due to kinship endogamy despite the occurrence of dispersal.

Interesting excerpts:

Two cultural groups, which matrimonial systems are reported to differ, coexist in Inner Asia: Turko-Mongols are described as mainly exogamous while Indo-Iranians are thought to be mainly endogamous45. However, it is not always clear if exogamy refers to clan (ethnic) or village (geographical) exogamy. Here, we used a dataset of 16 populations representing 11 different ethnic groups from both cultural groups and we quantified geographical exogamy rates and distances in each population. Using an empirical threshold of 4 km, we confirmed that matrimonial behaviours differ as described in the literature, even though we found some exceptions: three Turko-Mongol populations (out of 14) have less than 50% exogamy, whereas one Indo-Iranian population (out of four) has more than 50% exogamy.(…).

geographic-distance-turko-mongols-indo-iranian
Geographical distances between the birth places of couples in Turko-Mongols and Indo-Iranians. The geographical distances are plotted in log scale (km). Their densities are represented by population (dashed lines) or for the Indo-Iranian and Turko-Mongol groups (solid lines). We represented the average distances within couples per population using a Kernel’s density estimate implemented in R with a smoothing bandwidth of 0.2. See Supplementary Table 1B for population codes.

An additional important result of our study is that geographical distances are not negatively correlated with inbreeding, as could have been expected under an isolation-by-distance model65. Interestingly, a recent study based on a large genealogical dataset, collected across Western Europe and North America, and including birth places information, similarly found an absence of correlation between relatedness and the distance between couples, for the cohorts born before 185066. Our analyses within present-day Turko-Mongols reveal more specifically that the structure of the relationship between geographical distance and mating choice inbreeding is not linear, but rather tends to be bell-shaped, and thus cannot be correctly assessed with a single correlation test. Indeed, descendants from parents born 4 to 40 km apart are more inbred than descendants from endogamous couples (≤4 km) or from long-range exogamous ones (>40 km). As a consequence, close inbreeding exists despite geographical exogamy, and about a third of descendants from exogamous couples are inbred.

These results, in addition to those obtained by [Kaplanis et al. 2018]66, highlight the importance of using geographic distances rather than exogamy rates to characterize the impact of exogamy on inbreeding, as already described when studying patrilocality67. Indeed, when we compare mating choice inbreeding patterns for descendants from exogamous and endogamous couples defined for thresholds of 4, 10, 20 and 30 km, we find no significant differences (for number and total length of class C-ROHs and F-Median coefficient: MWU test p-values > 0.1). We only detect significantly lower values in descendants from exogamous couples for larger distances above 40 and 50 km (p-values < 0.03).

genetic-diversity-turko-mongol-indo-iranian
Genetic diversity (A) and inbreeding patterns (B,C) within populations. Grey lines in (B) represent inbreeding values corresponding to second-cousins and first-cousins. The grey line in (C) represents the homozygosity population baseline expected under panmixia. The number of samples per population is indicated between parentheses. See Supplementary Table 1B for population codes.

Our results also challenge the intuition that exogamy necessarily increases the genetic diversity within a population and therefore reduces drift inbreeding. Indeed, we found that Turko-Mongol populations have a lower genetic diversity (as measured by the mean haplotypic heterozygosity) and more intermediate ROHs associated with drift inbreeding than those of Indo-Iranians despite higher exogamous rates. (…)

Overall, this research sheds light on mating choice preferences: we showed that two thirds of partners that have not dispersed did mate with unrelated individuals, and that drift and mating choice inbreeding is variable, even among close-by populations. We also provide new insights into the relationship between dispersal and inbreeding in humans, based on genetic data, and demonstrate that geographical exogamy is not necessarily negatively associated with mating choice inbreeding, but rather can have a more complex non-linear relationship. Contrary to the common situation in many animals, this finding suggests that Inner Asian human populations who practise exogamy at small geographical scales might be focused on alliance strategies that result in kinship endogamy. (…)

Related:

On Latin, Turkic, and Celtic – likely stories of mixed societies and little genetic impact

celtic-europe-national-geographic

Recent article on The Conversation, The Roman dead: new techniques are revealing just how diverse Roman Britain was, about the paper (behind paywall) A Novel Investigation into Migrant and Local Health-Statuses in the Past: A Case Study from Roman Britain, by Redfern et al. Bioarchaeology International (2018), among others.

Interesting excerpts about Roman London:

We have discovered, for example, that one middle-aged woman from the southern Mediterranean has black African ancestry. She was buried in Southwark with pottery from Kent and a fourth century local coin – her burial expresses British connections, reflecting how people’s communities and lives can be remade by migration. The people burying her may have decided to reflect her life in the city by choosing local objects, but we can’t dismiss the possibility that she may have come to London as a slave.

The evidence for Roman Britain having a diverse population only continues to grow. Bioarchaeology offers a unique and independent perspective, one based upon the people themselves. It allows us to understand more about their life stories than ever before, but requires us to be increasingly nuanced in our understanding, recognising and respecting these people’s complexities.

We already have a more or less clear idea about how little the Roman conquest may have shaped the genetic map of Europe, Africa, or the Middle East, in contrast to other previous or later migrations or conquests.

Also, on the Turkic expansion, the recent paper of Damgaard et al. (Nature 2018) stated:

In the sixth century AD, the Hunnic Empire had been broken up and dispersed as the Turkic Khaganate assumed the military and political domination of the steppes22,23. Khaganates were steppe nomad political organizations that varied in size and became dominant during this period; they can be contrasted to the previous stateless organizations of the Iron Age24. The Turkic Khaganate was eventually replaced by a number of short-lived steppe cultures25 (…).

We find evidence that elite soldiers associated with the Turkic Khaganate are genetically closer to East Asians than are the preceding Huns of the Tian Shan mountains (Supplementary Information section 3.7). We also find that one Turkic Khaganate-period nomad was a genetic outlier with pronounced European ancestries, indicating the presence of ongoing contact with Europe (…).

turk-medieval-populations
Analyses of Turk- and Medieval-period population clusters. a, PCA of Tian Shan Hun, Turk, Kimak, Kipchack, Karakhanid and Golden Horde, including 28 individuals analysed at 242,406 autosomal SNP positions. b, Results for model-based clustering analysis at K = 7. Here we illustrate the admixture analyses with K = 7 as it approximately identifies the major component of relevance (Anatolian/ European farmer component, Caucasian ancestry, EHG-related ancestry and East Asian ancestry).”

These results suggest that Turkic cultural customs were imposed by an East Asian minority elite onto central steppe nomad populations, resulting in a small detectable increase in East Asian ancestry. However, we also find that steppe nomad ancestry in this period was extremely heterogeneous, with several individuals being genetically distributed at the extremes of the first principal component (Fig. 2) separating Eastern and Western descent. On the basis of this notable heterogeneity, we suggest that during the Medieval period steppe populations were exposed to gradual admixture from the east, while interacting with incoming West Eurasians. The strong variation is a direct window into ongoing admixture processes and the multi-ethnic cultural organization of this period.

We already knew that the expansion of the La Tène culture, associated with the expansion of Celtic languages throughout Europe, was probably not accompanied by massive migrations (from the IEDM, 3rd ed.):

The Mainz research project of bio-archaeometric identification of mobility has not proven to date a mass migration of Celtic peoples in central Europe ca. 4th-3rd centuries BC, i.e. precisely in a period where textual evidence informs of large migratory movements (Scheeres 2014). La Tène material culture points to far-reaching inter-regional contacts and cultural transfers (Burmeister 2016).

Also, from the latest paper on Y-chromosome bottleneck:

[The hypothesis of patrilineal kin group competition] has an added benefit in that it could explain the temporal placement of the bottleneck if competition between patrilineal kin groups was the main form of intergroup competition for a limited episode of time after the Neolithic transition. Anthropologists have repeatedly noted that the political salience of unilineal descent groups is greatest in societies of ‘intermediate social scale’ (Korotayev47 and its citations on p. 2), which tend to be post-Neolithic small-scale societies that are acephalous, i.e. without hierarchical institutions48. Corporate kin groups tend to be absent altogether among mobile hunter gatherers with few defensible resource sites or little property (Kelly49 pp. 64–73), or in societies utilizing relatively unoccupied and under-exploited resource landscapes (Earle and Johnson50 pp. 157–171). Once they emerge, complex societies, such as chiefdoms and states, tend to supervene the patrilineal kin group as the unit of intergroup competition, and while they may not eradicate them altogether as sub-polity-level social identities, warfare between such kin groups is suppressed very effectively51,52.These factors restrict the social phenomena responsible for the bottleneck to the period after the initial Neolithic but before the emergence of complex societies, which would place the bottleneck-generating mechanisms in the right period of time for each region of the Old World.

chalcolithic_late_Europe_Bell_Beaker
Diachronic map of Late Copper Age migrations including Classical Bell Beaker (east group) expansion from central Europe ca. 2600-2250 BC

However, I recently read in a forum for linguists that the expansion of East Bell Beakers overwhelmingly of R1b-L21 subclades in the British Isles “poses a problem”, in that it should be identified with a Celtic expansion earlier than traditionally assumed…

That interpretation would be in line with the simplistic maps we are seeing right now for Bell Beakers (see below for the Copenhagen group).

If anything, the results of Bell Beaker expansions (taken alone) would seem to support a model similar to Cunliffe & Koch‘s hypotheses of a rather early Celtic expansion into Great Britain and Iberia from the Atlantic.

invasion-from-the-steppe-yamnaya
Spread of Indo-European languages (by the Copenhagen group).

But it doesn’t. Mallory already explained why in Cunliffe & Koch’s series Celtic from the West: the Bell Beaker expansion is too early for that; even for Italo-Celtic. It should correspond to North-West Indo-European speakers.

Not every population movement that is genetically very significant needs to be significant for the languages attested much later in the region.

This should be obvious to everyone with the many examples we already have. One of the least controversial now would probably be the expansion of R1b-DF27, widespread in Iberia probably at roughly the same time as R1b-L21 was in Great Britain, and still pre-Roman Iberians showed a mix of non-Indo-European languages, non-Celtic languages (at least Galaico-Lusitanian), and also some (certain) Celtic languages. And modern Iberians speak Romance languages, without much genetic impact from the Romans, either…

It is well-established in Academia that the expansion of La Tène is culturally associated with the spread of Celtic languages in Europe, including the British Isles and Iberia. While modern maps of U152 distribution may correspond to the migration of early Celts (or Italo-Celtic speakers) with Urnfield/Hallstatt, the great Celtic expansion across Europe need not show a genetic influence greater than or even equal to that of previous prehistoric migrations.

post-bell-beaker-europe
Post-Bell-Beaker Europe, after ca. 2200 BC.

You can see in these de novo models the same kind of invented theoretical ‘problem’ (as Iosif Lazaridis puts it) that we have seen with the Corded Ware showing steppe ancestry, with Old Hittite samples not showing EHG ancestry, or with CHG ancestry appearing north of the Caucasus but no EHG to the south.

However you may want to explain all these errors in scientific terms (selection bias, under-coverage, over-coverage, faulty statistical methods, etc.), these interpretations were simply fruit of the lack of knowledge of the anthropological disciplines at play.

Let’s hope the future paper on Celtic expansion takes this into consideration.

Related:

Climatic conditions in the Cis-Ural Steppe region and the Repin culture

cis-ural-region

New paper (behind paywall) Climate and Vegetation Changes over the Past 7000 Years in the Cis-Ural Steppe, by Khokhlova, Morgunova, Khokhlov, and Gol’eva, Eurasian Soil Sc. (2018) 51: 506.

Abstract (emphasis mine):

A multilayered archaeological site Turganik Settlement in the valley of the Tok River in the Cis- Ural steppe (Orenburg oblast) was examined with the use of paleopedological and microbiomorph methods. Ancient people inhabited this area in the Latest Neolithic (Eneolithic) (5th millennium BC) and Early Bronze (4th millennium BC) ages. It was found that cultural layers dating back to the Atlantic period of the Holocene had been formed under conditions of a predominance of grassy–forb vegetation with a small portion of tree species and dry climate; the ancient settlement was not affected by floods and was suitable for permanent living. It is probable that soils of the chestnut type with salinization and solonetzic features were developed in that time. The final stages of the accumulation of cultural layers were marked by strong shortterm floods, whose sediments partly masked the features of the previous long arid epoch. The highest degree of aridity was at the end of the Atlantic period. In the Subboreal and Subatlantic periods, soils of the meadowchernozemic type were formed; the spore–pollen spectra of these periods are characterized by a higher portion of tree species and by the presence of phytoliths of meadow grasses. The climatic conditions were generally colder and more humid, though some short-term aridization stages could take place. Some of these stages are recorded in the thickness of the studied sediments.

Interesting excerpts:

Paleosols buried under archaeological monuments of different periods represent a valuable archieve of information about the paleoenvironment. Most of the works in the field of archaeological pedology deal with earthen burial sites and kurgans [2, 5, 7, 9, 11]. Paleosols buried under the kurgans present us the paleoenvironmental records of a relatively short time before they were buried under the kurgan bodies. The study of kurgans created in different times makes it possible to characterize paleosol sequences storing information on longer periods of time in the second half of the Holocene. However, groups of kurgans that were consecutively created during the entire time span of kurgan construction, beginning from about 6000 yrs BC to the Early Medieval epoch, are few in number [8, 18, 22]. Even for such groups of kurgans, there are considerable time intervals that cannot be characterized because kurgans were not constructed during them. Hence, it is impossible to study the soils buried during these intervals. To reconstruct paleoenvironmental conditions for them, certain interpolation is required [29].

At the same time, there are archaeological sites — ancient settlements — the material of which gradually accumulated during very long time, e.g., beginning from the Middle Holocene to the present. Though such objects may also contain “missing layers” for certain periods, when the processes of denudation, erosion, or deflation predominated over sediment accumulation, they represent an almost continuous record on information about the paleoenvironmental conditions from the beginning of their functioning [25]. The most valuable among such sites are those that retain information on those periods of the Holocene that cannot be characterized on the basis of available data on the paleosols buried under the kurgans. In particular, this is the Atlantic period (7500–5000 yrs ago), because the construction of kurgans began only in the second half of this period (within the Volga–Ural interfluve [14]), and such ancient kurgans are rarely found. We studied such an archaeological site in the valley of the Tok River in the Cis-Ural steppe zone in Orenburg oblast. This site is known as the ancient Turganik settlement.

We studied different layers of the Turganik settlement with the use of a set of methods in order reconstruct the paleoenvironmental conditions (climate and vegetation) for the entire period of the accumulation of these sediments.

Thus, the Atlantic period of the Holocene in the Cis-Uralian steppe was characterized by dry climatic conditions with the driest stage during the Early Bronze Age (the Early Yamnaya culture of the middle of the fourth millennium BC). The Subboreal and Subatlantic periods were generally colder and wetter, though they also included short-term aridization phases, some of which were recorded in the sediment thickness.

This site is at the core of the interaction of Samara, Khvalynsk, and Repin cultures during the Eneolithic.

You can read more about it and the nature of Repin described by Morgunova (in favour of Gimbutas’ model), as combining traditions from Eneolithic steppe cultures from Khvalynsk to Sredni Stog, e.g. in Pottery from the Volga area in the Samara and South Urals region from Eneolithic to Early Bronze Age (2015).

repin-khvalynsk
Eneolithic settlements (1–5, 7, 10–16, 20, 22–43, 48, 50), burial grounds (6, 8–9, 17–19, 21, 47, 49) and kurgans (44–46) of the steppe Ural-Volga region: 1 Ivanovka; 2 Turganik; 3 Kuzminki; 4 Mullino; 5 Davlekanovo; 6 Sjezheye (burial ground); 7 Vilovatoe; 8 Ivanovka; 9 Krivoluchye; 10–13 LebjazhinkaI-III-IV-V; 14 Gundorovka; 15–16 Bol. Rakovka I-II; 17–18 Khvalunsk I-II; 19 Lipoviy Ovrag; 20 Alekseevka; 21 Khlopkovskiy; 22 Kuznetsovo I; 23 Ozinki II; 24 Altata; 25 Monakhov I; 26 Oroshaemoe; 27 Rezvoe; 28 Varpholomeevka; 29 Vetelki; 30 Pshenichnoe; 31 Kumuska; 32 Inyasovo; 33 Shapkino VI; 34 Russkoe Truevo I; 35 Tsaritsa I-II; 36 Kamenka I; 37 Kurpezhe-Molla; 38 Istay; 39 Isekiy; 40 Koshalak; 41 Kara-Khuduk; 42 Kair-Shak VI; 43 Kombakte; 44 Berezhnovka I-II; 45 Rovnoe; 46 Politotdelskoe; 47 burial near s. Pushkino; 48 Elshanka; 49 Novoorsk; 50 Khutor Repin.

The migration model of Anthony (2007, 2015), who collaborated with this group, is a more precise description of how peoples from the east of the Don River (mainly Khvalynsk/Repin cultures) migrated to develop a greater Yamna community, with Repin-type material culture expanding east of the Urals (into Afanasevo) and west of the Don River (into previous Sredni Stog/Kvitjana territory) – which I followed for the Indo-European demic diffusion model (we have recent samples of other potential Khvalynsk/Repin-related migrations).

NOTE. I usually refer to this Khvalynsk/Repin migration in genomics as of ‘Khvalynsk migrants’, for simplicity purposes, given that the few samples we have are from Khvalynsk, and that cultural regions east of the Don are difficult to differentiate precisely. However, it remains to be seen if – as I proposed – there are genetic differences between Repin and Khvalynsk groups, especially regarding R1b-L23 subclades – I proposed mainly Z2103 for Khvalynsk, L51 for Repin, a difference which has not been confirmed for the moment in Afanasevo, probably of Pre-Tocharian dialect, an archaic Northern dialect of Late PIE.

Anthony’s model of Khvalynsk/Repin as Yamna forefathers is probably, as we are seeing in Yamna samples, the right interpretation of peoples behind pots, compared to Gimbutas’ general idea of expanding kurgans of the 1970s.

On the other hand, the alternative Russian school version of Yamna developing from a heterogeneous community of Khvalynsk-Sredni Stog-Lower Danube cultures is probably by now to be fully dismissed, in archaeology (as Morgunova says) as in genetics.

Related:

Brexit forces relocation of one of today’s main Yamna research projects to Finland

yamnaya_distribution

Archaeologist Volker Heyd is bringing his ERC Advanced Grant to Helsinki. So has proudly reported the University of Helskinki.

Some interesting excerpts (emphasis mine):

With his research group, Heyd wants to map out how the Yamnaya culture, also known as the Pit Grave culture, migrated from the Eurasian steppes to prehistoric south-eastern Europe approximately 3,000 years BCE. Most of the burial mounds typical of the Yamnaya culture have already been destroyed, but new techniques enable their identification and study.

The project is using multidisciplinary methods to solve the mystery. Archaeologists are collaborating with scholars of biological and environmental sciences, using the methods of funerary archaeology, landscape archaeology and remote sensing that are at the group’s disposal. From the field of biological sciences, the group is making use of genetics/DNA analysis, biological anthropology and biogeochemistry. As for environmental sciences, their contribution is in the form of palaeoclimatology, which studies climate before modern meteorological observations, and soil formation processes.

The project, coordinated by the discipline of archaeology at the University of Helsinki, will also welcome researchers from Mainz, London, Bristol and Budapest, in addition to which the group will collaborate with Czech, Slovak and Polish colleagues. Field studies and sample collection for the project will be conducted in Romania, Bulgaria, Hungary and Serbia.

In Helsinki, Volker Heyd’s main collaborator is Professor Heikki Seppä from the Department of Geosciences and Geography on the Kumpula Campus, while the team will also be hiring three postdoctoral researchers.

yamna-bell-beaker
Yamna – East Bell Beaker migration 3000-2300 BC, after Heyd (2007, 2012)

Yam­naya from the east changed Europe forever

The researchers wish to understand how the Yamnaya migrated to Europe and how the arrival of a new culture changed an entire continent.

How many people actually arrived? Taking the scale of the changes, some estimates range in the millions, but according to Volker Heyd, the number of people representing the Yamnaya culture in southeast Europe was around several ten thousands. It is indeed remarkable how such a relatively small group of people has had such a significant and far-reaching impact on Europe.

The Yamnaya also brought with them new cultural and social norms that have had far-reaching consequences. For instance, patriarchy and monogamy seems to be part of the Yamnaya legacy. Another established theory speculates that marriages made women migrate and travel even across great distances.

In accordance with primogeniture, the first-born son of the family inherited his parents’ possessions, while the younger siblings had to make their own way through other means. Among other things, this practice guaranteed ample human resources for the legions of the Roman Empire, which enabled its establishment and expansion, and later filled the ranks of medieval monasteries across Europe.

Another interesting question is what made representatives of the Yamnaya culture migrate from the eastern European steppes to the west. Heyd believes that the underlying reason may have been climate change. The Yamnaya were almost exclusively dependent on animal husbandry. As the climate changed – when rainfalls decreased in the east – they may have been forced to migrate west to secure the welfare of their cattle.

North-East Europe and Corded Ware

Heyd has already been here as a visiting professor in the Helsinki University Humanities programme since the beginning of the year, working on another project. Together with Postdoctoral Researcher Kerkko Nordqvist, he is investigating the prehistoric settlement of north-eastern Europe 3,000 – 6,000 years ago with research methods similar to the new Yamnaya project. One of their central research questions is what made people migrate to this region, and which innovations they brought with them. In this case also, the reasons behind the migration may be related to changes in the environment and climate.

This is probably bad news for research in the UK (I say probably because I guess many Brexiteers will be happy to have less foreign researchers in their country), but it is great news to see both researchers, Heyd and Nordqvist (whose Ph.D. thesis includes research on the Corded Ware culture that I have recently mentioned) – , be able to collaborate together to assess Indo-European and Uralic migrations.

Heyd’s website at the University of Bristol states that he is currently working on:

  1. The Milking Revolution in Temperate Neolithic Europe (NeoMilk)‘. Funded by an ERC Advanced Grant, European Union, to R. Evershed. See, for further information: www.neomilk-erc.eu
  2. The Yamnaya Impact‘: Archaeology and scientific research of/into the Yamnaya populations of Southeastern Europe and their impact on contemporary local and neighboring 3rd millennium BC societies as well as their role in the emergence of the Corded Ware and Bell Beaker complexes in Europe.
  3. The Prehistoric Peopling of Northeastern Europe‘: Inter-/crossdisciplinary studies on the archaeology, anthropology, linguistics, and bio- and environmental sciences of early Uralic speakers and their first horizon of interactions with Indo-European speakers. This wider project is in cooperation with colleagues from Helsinki and Turku Universities in Finland, as well as from Russia, Estonia and Poland.
  4. Czech Republic‘: I am closely cooperating with the Institute of Archaeology, Czech Academy of Sciences, in Prague for two research projects funded by the Czech Grant Agency in which we measure various isotopes from human remains in Bristol to understand past mobility and diet. The Humboldt-Kolleg -conference ‘Reinecke’s Heritage’ (with P. Pavúk, M. Ernée and J. Peska) held in June 2017 at Chateau Křtiny/Moravia is also part of this cooperation. See, for further information: http://ukar.ff.cuni.cz/reinecke.
yamna-late-proto-indo-european
Image modified from Narasimhan et al. (2018), including the most likely proto-language identification of different groups. Original description “Modeling results including Admixture events, with clines or 2-way mixtures shown in rectangles, and clouds or 3-way mixtures shown in ellipses”. See the original full image here.

On the genetic aspect, we have gross Yamna migrations today as clearly depicted as they will ever be: late Khvalynsk/Yamna expanded Late Proto-Indo-European languages, and Bell Beakers brought North-West Indo-European to almost all of Europe, as predicted in Harrison and Heyd (2007). Full stop.

There is still fine-grained population structure, though, as Lazaridis puts it, to be detected in migratory movements contemporary or subsequent to the Yamna settlements in South-East Europe and the East Bell Beaker expansion.

We will probably lack a comprehensive description of local archaeological cultural exchanges – to fit the potential dialectal developments and expansions – to be coupled with small-scale migratory movements in genetics, as more samples are made available.

This work from the University of Helsinki will hopefully provide the necessary detailed anthropological foundations to be used with future genetic studies to obtain a more precise picture of the formation and expansion of North-West Indo-Europeans.

Related:

Human dietary evolution in central Germany, and relationship of Únětice to Corded Ware and Bell Beaker cultures

bronze_age_early_Unetice.

Open access 4000 years of human dietary evolution in central Germany, from the first farmers to the first elites, by Münster et al. PLOS One (2018).

Excerpts (emphasis mine):

This study of human diet between the early stages of the farming lifestyle and the Early Bronze Age in the MES, based on carbon and nitrogen isotope analyses, is amongst the most comprehensive of its kind. Or results show that human dietary behaviour has changed significantly throughout the study period. A distinct increase in the proportion of animal protein in the human diet can be identified over time, a trend which only the people from the BBC did not follow. The results of the stable isotope analyses are consistent with epidemiological data on caries frequency, which indicate the highest proportions of carbohydrates in the human diet in the EN and the lowest in the EBA [19]. These findings may have been due to an increased consumption of either meat or dairy products. Although meat and dairy consumption cannot be distinguished by means of stable isotope data or caries frequency, molecular-genetic analyses of lactase persistence argue against an increased consumption of fresh milk [9]. However, although approximately 70% of the world population has a lactose intolerance, most of them can tolerate dairy foods or lactose-containing foods without developing symptoms [128]. It therefore comes as no surprise that the use of processed milk, i.e. dairy products, appears to have set in early on in the Neolithic period [99]. Unarguably, there was an increasing stabilisation of the supply of meat and secondary animal products throughout the Neolithic. The data dynamics overall argue against an equal availability of animal-derived protein to all sections of the various populations, which attests to early processes of specialisation, individualisation and hierarchisation. Moreover, population-genetic processes are also reflected in the development of human dietary habits. From the 4th millennium BC onwards, groups moved into the MES from the north, sometimes accompanied by violence [6,29], and fundamental demographic changes took place in the FN with the arrival of CWC groups from the north-eastern steppes and the BBC from south-western Europe [6,7]. This former pastoral steppe component, in particular, may have been responsible for the fact that animal-based foodstuffs reached their highest importance in the FN and EBA. Differences in the consumption of animal-derived products between the sexes resulted in significantly lower δ15N values and less access to animal protein in females. Besides behavioural choices as to what food to consume, numerous other nutritional and gender-specific factors must certainly be taken into account when assessing the subsistence and nutritional balance of individuals. In the future, analysis of single amino acids of nitrogen and the compound-specific carbon isotope analysis of lipids and bone mineral may help providing more detailed and nuanced insight on aspects of human diet, such as protein sources in complex foodwebs, nutritional stress and disease [129131]. They should become a standard in isotope studies and applied more often and routinely.

saxony-anhalt-final-neolithic-cultures
Overview of investigated sites and archaeological chronology of Neolithic and Early Bronze Age central Germany. The Stroke Ornamented Culture and Michelsberg Culture are not represented in our sample due to low rate of anthropological findings. Chronology after Schwarz in [29]. https://doi.org/10.1371/journal.pone.0194862.g001

Regarding specifically differences between Corded Ware (CWC) and Bell Beaker (BBC) cultures in Saxony-Anhalt, a region already known to show a resurge of the previous population after the Únětice period:

Based on isotope data from collagen [104], a diet with a high protein content from meat or dairy products has been postulated for CWC groups from south-western Germany, though researchers there were also unable to distinguish between the two sources of protein. The consumption of fresh milk and the consumption of dairy products such as cheese, yoghurt and kefir may also be erroneously dated to the same period and associated with lactase persistence. A newly reported genome-wide SNP dataset from 230 West Eurasians dating from between 6,500 and 300 cal. BC [9] has shown, like earlier studies [105], that no notable increase in lactase persistence in Europe appears to have occurred prior to 2,000 BC. It was and is a fact that milk is not a natural foodstuff for adult consumption, unless one is prepared to negate the numerous symptoms of lactose intolerance, including abdominal pain, bloating, flatulence, diarrhoea, asthma and others. Cultural evolution in conjunction with natural selection has made it possible for us to use milk and its secondary products as a source of protein and energy. Whilst the continuous increase in animal protein in the diet of the Neolithic populations of the MES from the LBK to the Early Bronze Age can undoubtedly partly be traced back to an intensified use of secondary animal products over the course of the Neolithic, it is difficult to estimate how great a contribution this made to the increase in δ15N values. Judging from molecular-genetic data on lactase persistence, however, the consumption of fresh milk, at least, appears to have first begun to have an impact on the protein balance of individuals around 4,000 years ago [9].

NOTE. Regarding lactase persistence, we now know that Ukraine_Eneolithic sample I6561, of haplogroup R1a-Z93 (hence probably related to the later expansion of the Corded Ware culture) is the nearest sample to the population that might have expanded the 13910*T lactase persistence allele in Northern Europe.

neolithic-differences-male-female
Sex-specific differences in stable carbon and nitrogen isotope values in humans. https://doi.org/10.1371/journal.pone.0194862.g004

[After the massive influx of the CWC into central Europe in the FN] The dietary profile once again exhibits an increase in the mean δ15N values, to 10.1 ± 1.0 ‰. The BBC, which spread somewhat later throughout north and central Europe (with the arrival of the CWC jointly making up Event C) and whose origins are presumed to have been in south-western Europe, constitutes an exception, not just from the point of view of genetics. In contrast to the general diachronic trend consisting of raised δ15N values in the cultural groups examined, the BBC exhibited a nutritional decrease in mean δ15N values to 9.7 ± 0.7 ‰. The divergence between the CWC and the BBC to be seen in their funerary rites, despite their chronological and sometimes also territorial coexistence, is thus also visible in their dietary habits. Comparative examinations of CWC sites in southern Germany have shown that their mean δ15N values were, in fact, comparable to those of the CWC in the MES (δ13C: -19.9 ± 0.6 ‰, δ15N: 10.8 ± 0.7 ‰, n = 32), despite exhibiting significant variation between and even within the sites, thus pointing to the diverging subsistence strategies of different communities [104]. The UC, which followed the CWC in the MES, bore close affinities to its forerunner in terms of its population genetics, thus supporting the hypothesis that the BBC only had a minimal genetic impact on the UC [6,7]. The close genetic links between the UC and the CWC, however, are also seen in very similar mean nitrogen values which, at 10.4 ± 0.7 ‰, were the highest in the overall sample. Moreover, a striking aspect in the evaluation of the mean δ15N values over time is a clear tendency towards rising standard deviations (S4 Fig). It is highly likely that this reflects increased social differentiation in society at the end of the Neolithic and in the Early Bronze Age. Socioeconomic advancement led to differences in status within communities and even to the formation of an elite, the differences applying to numerous facets of life, including dietary habits [60].

saxony-anhalt-N-values
Chronological development of the distribution of δ15N-values according to the different archaeological periods. >Numbers of individuals are displayed in parentheses. https://doi.org/10.1371/journal.pone.0194862.g007

I think the overstudied region of Saxony-Anhalt and the Tollense valley region may not be exactly where the Proto-Balto-Slavic homeland actually formed, but they are certainly showing interesting hints to how (and where approximately) it might have happened…

Related:

Integrative studies of cultural evolution: crossing disciplinary boundaries to produce new insights

Interesting open access article Integrative studies of cultural evolution: crossing disciplinary boundaries to produce new insights, Oren Kolodny, Marcus W. Feldman, Nicole Creanza, Philos. Trans. Royal Soc. B (2018).

Abstract:

Culture evolves according to dynamics on multiple temporal scales, from individuals’ minute-by-minute behaviour to millennia of cultural accumulation that give rise to population-level differences. These dynamics act on a range of entities—including behavioural sequences, ideas and artefacts as well as individuals, populations and whole species—and involve mechanisms at multiple levels, from neurons in brains to inter-population interactions. Studying such complex phenomena requires an integration of perspectives from a diverse array of fields, as well as bridging gaps between traditionally disparate areas of study. In this article, which also serves as an introduction to the current special issue, we highlight some specific respects in which the study of cultural evolution has benefited and should continue to benefit from an integrative approach. We showcase a number of pioneering studies of cultural evolution that bring together numerous disciplines. These studies illustrate the value of perspectives from different fields for understanding cultural evolution, such as cognitive science and neuroanatomy, behavioural ecology, population dynamics, and evolutionary genetics. They also underscore the importance of understanding cultural processes when interpreting research about human genetics, neuroscience, behaviour and evolution.

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Differences in ADMIXTURE between Khvalynsk/Yamna and Sredni Stog/Corded Ware

neolithic-steppe

Looking for differences among steppe cultures in Genomics is like looking for a needle in a haystack.

It means, after all, looking for differences among closely related cultures, such as between South-Western and North-Western Anatolian Neolithic cultures, or among Old European cultures (such as Vinča or Cucuteni–Trypillia), or between Iberian cultures after the arrival of steppe-related populations.

These differences between closely related regions, in all these cases and especially among steppe cultures, even when they are supported by Archaeology and anthropological models of migration (and compatible with linguistic models), are expected to be minimal.

Fortunately, we have phylogeography, which helps us point in the right direction when assessing potential migrations using genomic data.

User Tomenable recently pointed out a curious finding on Anthrogenica, from data available in Mathieson et al (2017): in ADMIXTURE results with K=12, a different ancestral component (in light green in the paper, see below) is traceable from the North Caspian steppe since the Neolithic. This is also partially distinguishable on K=10 and K=11, although not so clearly differentiating among later cultures.

NOTE: Read more on the controversy regarding the ideal number of ancestral populations, the absurd use of ADMIXTURE to solve language questions, and the meaning of cross-validation (CV) values

admixture-khvalynsk-yamna-sredni-stog-cwc
Unsupervised ADMIXTURE plot from k=10 to 12, on a dataset consisting of 1099 present-day individuals and 476 ancient individuals. We show newly reported ancient individuals and some previously published individuals for comparison.

Explanations for this finding might include, as the user points out, a greater contribution of CHG ancestry in the eastern steppe cultures (Khvalynsk/Yamna) compared to the North Pontic steppe (Sredni Stog/Corded Ware), which is probably one of the main genomic differences among both cultures, as I pointed out in the Indo-European demic diffusion model (see accounts on the origins of Khvalynsk and Sredni Stog populations and on contacts between Yamna and the Caucasus, and see below also my sketch of Eurasian genomic history).

Interesting is also the appearance of similar ancestral components later in Vučedol – which probably received admixture from Yamna settlers (see admixture components in West Yamna samples and in the Yamna settler from Bulgaria) – , and later still in the Balkans.

On the other hand, previous ancestral components in outliers from the Balkans seem to be more similar to Sredni Stog samples, giving still more strength to the hypothesis that this common (“steppe”) component expanded westward within the Pontic-Caspian steppe with the spread of Suvorovo-Novodanilovka chiefs.

Problems with this interpretation include:

1) The scarce samples available, the different cultures included, and the CV values of the K populations selected in ADMIXTURE.

2) The lack of data for comparison with Bell Beaker peoples (from Olalde et al. 2017).

3) The sample classified as Latvia_LN/CWC has this component. I have already said before that, given the differences with all other Corded Ware samples, this quite early sample might be an outlier, with Khvalynsk/Yamna population connected directly to the ancestors of this individual, possibly through exogamy (as it is clear from my sketch below). Whether or not this is an outlier among CWC populations in the Baltic, only future samples can tell.

4) Three later individuals from Corded Ware in Germany have the component, in a minimal amount. I would bet – judging by their position in the graphic – that this might be explained through the Esperstedt family. These individuals might have in turn got the contribution directly from the oldest member, who shows what seems (in PCA) like a recent admixture from contemporary steppe cultures (such as the Catacomb culture).

NOTE: See my graphics with interesting members of the Espersted family marked: ADMIXTURE and PCA (outlier).

qgraph-eurasia
Tentative sketch modelling the genetic history of Europe and West Eurasia from ancient populations up to the Neolithic, according to results in recent genetic papers and archaeological models of known migrations.

Again, needle in a haystack… And confirmation bias by me, indeed.

But interesting nonetheless.

EDIT (4 JAN 2017): A reader points out that the interpretation of Unsupervised ADMIXTURE should work backwards (i.e. different contributions into different modern populations), and not based solely on ancestral populations, which seems probably right. So again, confirmation bias (and potentially wrong direction fallacy) by me…

Related:

Bell Beaker/early Late Neolithic (NOT Corded Ware/Battle Axe) identified as forming the Pre-Germanic community in Scandinavia

copper-age-late-bell-beaker

I wrote recently about the newly created Indo-European Corded Ware Theory group, which represents today the last dying effort to sustain the outdated model of the ‘Kurgan peoples’.

Archaeology and Linguistics (like Genetics) keeps slowly but relentlessly rejecting all the Kurgan model‘s foundations, safe for the steppe origin of Indo-European expansion.

The book Language and Prehistory of the Indo-European Peoples. A Cross-Disciplinary perspective. Eds. A. Hyllested, B.N. Whitehead, Th. Olander and B. Anette. Copenhagen Studies in Indo-European. Museum Tusculanum Press, Copenhagen, has been recently published (December 2017).

In it, Christopher Prescott contributes to the history of Indo-European migrations to Scandinavia and the formation of a common Nordic language, ancestral to Proto-Germanic.

A draft of his chapter is downloadable in Academia.edu: Dramatic beginnings of Norway’s history? Archaeology and Indo-Europeanization.

Here are some excerpts from the text:

Thus archaeology can deal with the question of Indo-Europeans through material culture, and archaeology can contribute to unraveling the events leading up to the fact that Indo-European languages were spread from the Indian Ocean to the northwestern European Arctic in pre- and proto-history. In 1995, Prescott and Walderhaug tentatively argued that a dramatic transformation took place in Norway around the Late Neolithic (2350 BCE), and that the swift nature of this transition was tied to the initial Indo-Europeanization of southern and coastal Norway, at least to Trøndelag and perhaps as far north as Troms. Although this interpretation cannot be “proven” in any positivist sense of the word (though aDNA and isotope studies have added a new layer of relevant data), in light of the last ten years of research and excavations, it is has become an increasingly reasonable hypothesis (e.g., Engedal 2002, Fari 2006, Håland and Håland 2000, Kristiansen 2004, Melheim 2006, Østmo 1996, also Kvalø 2007, Larsson 1997).

(…)

The Late Neolithic transformation gives rise to a cultural platform where most of southerly Norway is incorporated into the Nordic sphere. Interaction is no longer over borders, rather within a common cultural arena. Locally, the cultural institutions provide a base for the continued dynamic development through the Late Neolithic and Bronze Age. On a larger geographic and historical scale, incorporation into this field of interaction opens even the most peripheral parts of southern Norway to the streams of culture and events that shape Europe’s Bronze Age history, for example those originating from within Unetice, Tumulus Culture, Urnfeld and Hallstatt.

(…)

Changes in Scandinavia Norway are linked to wider transformations in Europe. Culturally, both Corded Ware Battle Axe and the Bell Beaker are important referential easterly and westerly European cultural horizons. Both these horizons affect and transform Northern Europe, so developments in Norway are not isolated affairs. Needless to say, though often regarded as Indo-European, the processes leading to and the affect of these cultural horizons is discussed for other parts of Europe as well (Mallory 1989:243ff).

Though there are reasonable arguments to assign both Corded Ware groups and bell Beaker groups Indo-European affiliations, the Corded Ware/Battle Axe horizon did not transform large parts of the Scandinavian Peninsula, nor can this horizon be identifies as the source of the practices, forms and institutions that characterize the ensuing Late Neolithic and Bronze Age. The Bell Beaker/early Late Neolithic, however, represents a source and beginning of these institution and practices, exhibits continuity to the following metal age periods and integrated most of Northern Europe’s Nordic region into a set of interaction fields. This happened around 2400 BCE, at the MNB to LN transition.

Though much is tentative and conjecture, multiple sources indicate that ideology, cosmology, myths social organization and probably language were Indo-European in the Bronze Age, and the development of the Bronze Age is rooted in the preceding Late Neolithic. Though the evidence also indicates that the initial Indo-European encounters, indeed “colliding worlds”, were probably experienced in the Middle Neolithic B, the archaeological record points to the time around transition to the Late Neolithic as the chronologically defining threshold for the entrenchment of an Indo-European platform throughout what would become the Nordic Bronze Age region in Norway. The Late Neolithic is therefore the most likely candidate for the introduction of the foundation for economic, social and ideological institutions, that is Giddens’ “deeply layered structure[s]”, that are fundamental to the development of the region’s identities, also ethnic, in the millennia to come.

early-bronze-age-europe
Diachronic map of migrations in Europe ca. 2250-1750 BC, after the Bell Beaker invasion, the most likely time of formation of a common Nordic language, ancestor of Proto-Germanic.

Mind you, not that these actual archaeological and linguistic models will deter anyone from supporting ancestry-based tentative sketches of a fictional ‘kurgan people’ that became outdated almost 60 years ago now – especially if they fit certain desires of ancestral ethnolinguistic identification with modern populations…

Related:

Coexistence of two different populations in Gotland during the Middle Neolithic

neolithic

New insights on cultural dualism and population structure in the Middle Neolithic Funnel Beaker culture on the island of Gotland, by Fraser et al., in Journal of Archaeological Science: Reports (2017).

Abstract (emphasis mine):

In recent years it has been shown that the Neolithization of Europe was partly driven by migration of farming groups admixing with local hunter-gatherer groups as they dispersed across the continent. However, little research has been done on the cultural duality of contemporaneous foragers and farming populations in the same region. Here we investigate the demographic history of the Funnel Beaker culture [Trichterbecherkultur or TRB, c. 4000–2800 cal BCE], and the sub-Neolithic Pitted Ware culture complex [PWC, c. 3300–2300 cal BCE] during the Nordic Middle Neolithic period on the island of Gotland, Sweden. We use a multidisciplinary approach to investigate individuals buried in the Ansarve dolmen, the only confirmed TRB burial on the island. We present new radiocarbon dating, isotopic analyses for diet and mobility, and mitochondrial DNA haplogroup data to infer maternal inheritance. We also present a new Sr-baseline of 0.71208 ± 0.0016 for the local isotope variation. We compare and discuss our findings together with that of contemporaneous populations in Sweden and the North European mainland.

The radiocarbon dating and Strontium isotopic ratios show that the dolmen was used between c. 3300–2700 cal BCE by a population which displayed local Sr-signals. Mitochondrial data show that the individuals buried in the Ansarve dolmen had maternal genetic affinity to that of other Early and Middle Neolithic farming cultures in Europe, distinct from that of the contemporaneous PWC on the island. Furthermore, they exhibited a strict terrestrial and/or slightly varied diet in contrast to the strict marine diet of the PWC. The findings indicate that two different contemporary groups coexisted on the same island for several hundred years with separate cultural identity, lifestyles, as well as dietary patterns.

gotland-funnel-beaker-culture
“Map indicating distribution of TRB-North group megalithic tombs (Blomqvist, 1989; Midgley, 2008; Sjögren, 2003; Tilley, 1999) and PWC areas (Larsson, 2009) modified from (Malmström et al., 2009). Swedish megalithic TRB burial sites included in the analyses: 1. Gökhem passage grave, Falköping, Västergötland, 2. Alvastra dolmen, Östergötland, 3. Mysinge passage grave, Resmo, Öland, 4. Ansarve dolmen, Tofta, Gotland, and 5. the Ostorf TRB burial ground, Mecklenburg-Vorpommern, Germany.”

If you are interested in knowing more details about settlements on the island, I recommend you to read Early Holocene human population events on the island of Gotland in the Baltic Sea (9200-3800 cal. BP), by Jan Apel, downloadable here.

It is important to remember cases like this one when speaking about the steppe as representing a single culture and people, speaking the same language, no matter the period in question and the archaeological cultures involved…

Related:

Featured image: Diachronic map of Early Neolithic migrations ca. 5000-4000 BC.

Related:

Migration vs. Acculturation models for Aegean Neolithic in Genetics — still depending strongly on Archaeology

aegean-neolithic-anatolia

Recent paper in Proceedings of the Royal Society B: Archaeogenomic analysis of the first steps of Neolithization in Anatolia and the Aegean, by Kılınç et al. (2017).

Abstract:

The Neolithic transition in west Eurasia occurred in two main steps: the gradual development of sedentism and plant cultivation in the Near East and the subsequent spread of Neolithic cultures into the Aegean and across Europe after 7000 cal BCE. Here, we use published ancient genomes to investigate gene flow events in west Eurasia during the Neolithic transition. We confirm that the Early Neolithic central Anatolians in the ninth millennium BCE were probably descendants of local hunter–gatherers, rather than immigrants from the Levant or Iran. We further study the emergence of post-7000 cal BCE north Aegean Neolithic communities. Although Aegean farmers have frequently been assumed to be colonists originating from either central Anatolia or from the Levant, our findings raise alternative possibilities: north Aegean Neolithic populations may have been the product of multiple westward migrations, including south Anatolian emigrants, or they may have been descendants of local Aegean Mesolithic groups who adopted farming. These scenarios are consistent with the diversity of material cultures among Aegean Neolithic communities and the inheritance of local forager know-how. The demographic and cultural dynamics behind the earliest spread of Neolithic culture in the Aegean could therefore be distinct from the subsequent Neolithization of mainland Europe.

The analysis of the paper highlights two points regarding the process of Neolithisation in the Aegean, which is essential to ascertain the impact of later Indo-European migrations of Proto-Anatolian and Proto-Greek and other Palaeo-Balkan speakers(texts partially taken verbatim from the paper):

  • The observation that the two central Anatolian populations cluster together to the exclusion of Neolithic populations of south Levant or of Iran restates the conclusion that farming in central Anatolia in the PPN was established by local groups instead of immigrants, which is consistent with the described cultural continuity between central Anatolian Epipalaeolithic and Aceramic communities. This reiterates the earlier conclusion that the early Neolithisation in the primary zone was largely a process of cultural interaction instead of gene flow.
aegean-neolithic-pca
Principal component analysis (PCA) with modern and ancient genomes. The eigenvectors were calculated using 50 modern west Eurasian populations, onto which genome data from ancient individuals were projected. The gray circles highlight the four ancient gene pools of west Eurasia. Modern-day individuals are shown as gray points. In the Near East, Pre-Neolithic (Epipaleolithic/Mesolithic) and Neolithic individuals genetically cluster by geography rather than by cultural context. For instance, Neolithic individuals of Anatolia cluster to the exclusion of individuals from the Levant or Iran). In Europe, genetic clustering reflects cultural context but not geography: European early Neolithic individuals are genetically distinct from European pre-Neolithic individuals but tightly cluster with Anatolians. PPN: Pre-Pottery/Aceramic Neolithic, PN: Pottery Neolithic, Tepecik: Tepecik-Çiftlik (electronic supplementary material, table S1 lists the number of SNPs per ancient individual).
  • The realisation that there are still two possibilities regarding the question of whether Aegean Neolithisation (post-7000 cal BC) involved similar acculturation processes, or was driven by migration similar to Neolithisation in mainland Europe — a long-standing debate in Archaeology:
    1. Migration from Anatolia to the Aegean: the Aegean Neolithisation must have involved replacement of a local, WHG-related Mesolithic population by incoming easterners. Central Anatolia or south Anatolia / north Levant (of which there is no data) are potential origins of the components observed. Notably, the north Aegeans – Revenia (ca. 6438-6264 BC) and Barcın (ca. 6500-6200 BC) – show higher diversity than the central Anatolians, and the population size of Aegeans was larger than that of central Anatolians. The lack of WHG in later samples indicates that they must have been fully replaced by the eastern migrant farmers.
    2. Adoption of Neolithic elements by local foragers: Alternatively, the Aegean coast Mesolithic populations may have been part of the Anatolian-related gene pool that occupied the Aegean seaboard during the Early Holocene, in an “out-of-the-Aegean hypothesis. Following the LGM, Aegean emigrants would have dispersed into central Anatolia and established populations that eventually gave rise to the local Epipalaeolithic and later Neolithic communities, in line with the earliest direct evidence for human presence in central Anatolia ca 14 000 cal BCE
  • On the archaeological evidence (excerpt):

    Instead of a single-sourced colonization process, the Aegean Neolithization may thus have flourished upon already existing coastal and interior interaction networks connecting Aegean foragers with the Levantine and central Anatolian PPN populations, and involved multiple cultural interaction events from its early steps onward [16,20,64,74]. This wide diversity of cultural sources and the potential role of local populations in Neolithic development may set apart Aegean Neolithization from that in mainland Europe. While Mesolithic Aegean genetic data are awaited to fully resolve this issue, researchers should be aware of the possibility that the initial emergence of the Neolithic elements in the Aegean, at least in the north Aegean, involved cultural and demographic dynamics different than those in European Neolithization.

    Featured image, from the article: “Summary of the data analyzed in this study. (a) Map of west Eurasia showing the geographical locations and (b) timeline showing the time period (years BCE) of ancient individuals investigated in the study. Blue circles: individuals from pre-Neolithic context; red triangles: individuals from Neolithic contexts”.

    Related: